1. Field of the Invention
The present invention relates to a method for creating three-dimensional data of a position of an outer periphery at the occlusal surface side of a keeper with respect to an abutment for an implant, and the three-dimensional data is used when the three-dimensional data of the abutment for an implant is created.
2. Description of the Conventional Art
Conventionally, a dental technician manually performs almost all processes of an operation for producing a dental prosthesis, such as an abutment or the like, used for an implant treatment. Thus, there is a problem that a skill level of a dental technician greatly affects a quality of a dental prosthesis to be produced. Therefore, a dental CAD/CAM system has been developed in order to acquire a dental prosthesis with a stable quality. The dental CAD/CAM system produces the dental prosthesis by the steps of measuring a model of a produced dental prosthesis by a three-dimensional measuring apparatus, and cutting a cutting block for dentistries based on the measured three-dimensional data by an automatic cutting machine.
For example, Japanese Patent Applications Laid-Open Nos. 2006-126004 and 2002-336277 disclose the three-dimensional measuring apparatuses used for the dental CAD/CAM system. The three-dimensional measuring apparatuses perform noncontact type measurement using laser or contact type measurement using a probe.
However, there is a problem such that the measuring methods can hardly measure an accurate shape of a concave part. That is, a dead area is readily made in the concave part, and a measurement error easily occurs when the concave part is formed at a steep gradient from an outer surface. Therefore, the conventional apparatuses can hardly measure the accurate shape of a concave part, regardless of the noncontact type or contact type.
As a retaining device for fixing a partial or full denture in an oral cavity, a permanent magnetic structure and a magnetic attachment have been developed rapidly and used widely. The permanent magnetic structure is made by covering a permanent magnet with a corrosion-resistant alloy or the like. The magnetic attachment uses magnetic attraction power applied between a keeper made of a soft magnetic body and the magnetic attachment.
When the magnetic attachment is used as the retaining device, there are various advantages. The magnetic attachment does not have parts to be abraded and damaged, unlike a mechanical retaining device such as a clasp or the like. Thus, the magnetic attachment can keep retaining force for a long period of time without decreasing the retaining force. When rotational force is applied to the magnetic attachment, the magnetic attachment can make the force to release, so that excess load is not applied to a supporting base. Since the attaching and detaching direction of the magnetic attachment is not restricted, a denture can be easily designed and produced. Furthermore, since the attachment and detachment of the magnetic attachment are easy and the retaining device has not a complex shape, the magnetic attachment has excellent cleaning property.
When the magnetic attachment is used for an implant, a keeper is embedded in the oral cavity inner side of an abutment arranged on the oral cavity inner side of an implant fixture implanted in a lost tooth part of a patient, and the permanent magnetic structure is embedded in an alveolar ridge side inner surface of a denture. When the magnetic attachment is used as the retaining device, there are such advantages compared with an implant treatment using conventional retaining devices that a problem hardly occurs even if the rising direction of the implant fixture is somewhat bad, and the magnetic attachment does not need connection unlike a bar attachment, so that the rising position is not restricted. Therefore, an implant treatment using the magnetic attachment as a retaining device for a denture has been widely used in recent years.
However, in the implant treatment using the magnetic attachment as a retaining device for a denture, a process for boring a keeper embedding part for embedding a keeper in an abutment is needed, and the keeper embedding part is a concave part. Thus, when the three-dimensional measuring device measures an abutment model having the keeper embedding part, the device can hardly measure an accurate internal shape of the keeper embedding part. As a result, the dental CAD/CAM system can hardly produce an abutment having an accurate shape.